Lower-alkyl cyclopentylmethyl, benzo-thiazolyl sulfenamides



States Patent Chemical Company, St. Louis, j M,o., a corporation of Delaware 3N0 Drawing. Application December ;10, 19.5.6

9 Claims. .(Cl. 260-93064?) The present invention relates-to anew class of beamfll a su enam de Whisha charact r ze as accelerato s Q 1 vu saniz on q whb sapo s ss n o s o ch s in pro r e .Many o d ruh s 1 1 ni n e z-sele to un o un el ar o act as t d l p to varying extents some vulcanization of the rubber compound during preliminary mixing and handling steps ,wheretherubbenstock is ;subjected.to temperatures somewhat below normal vulcanizing temperatures Suchconditions arecommonly ,known as. scorching tendency and such action results in the development of a finished product of somewhat inferior quality or, if the scorching is we e. m y re ul inry nin th ubbe ste Con q y the availab li o awele ers. p e yflin act on in. s e but it retarding a ti n du n t e han lin steps, is much to be desired.

The products of the present invention are characterized by possessing the general formula R--N--R where R represents afbengothiaz ole group which may be substitutedand. R represents a' cyclopentylmethylami ne nucleus. The benzpthiazole group includes Z-mercaptobenzothiazole and its ring substituted analogues such as alkyl, chlor, alkoxy, nitro and phenyl substituents thereof and their alkali salts, and the amine reacted therewith by the process set forth hereinafter includes the methyl, ethyl, propyl, .-isopropyl and fbutyl derivatives, all classitied as cyclopentylmethylamines. Examples ofthe new compounds, .all .of which are excellent accelerators vof the vulcanization of natural or synthetic sulfur vulcanizable hydrocarbon rubber-s comprise :N-.(2,3,3-trimethylcyclopentylmethyl)-2-benzothiazolesulfenamide, N-(2,2,3 -trimethylcyclopentylmethyl) -2-b enzothiazolesulfenamide, N- 1,4,5 ,5-tetramethylcyclopentylmethyl) .-2 .benzothiazolesulfenamide, N (1,3 dimethylcyclopentylmethyl) 2- methylbenzothiazolesulfenamide, and N-(1-methyl-3-isop py y peutvlrnpthyl) 2 -"bengothiaxolesulfenamide. 'llhe senew compounds may be preparedby the-oxidative gondensationof the cyclopentyla'rnine and mercaptobenzpt lgiazgle. The following typical examples illustrate suitabl s aiaa EXAMPLE 1.-PRODUCT A N 1 ,3-dime1lhylcycl0pentylmethyl) -2-benz0thiazolesulfenamide A solution was prepared by dissolving 43 parts (0.25 mole) of 97% mercaptobenzothiazole in 100 parts of water containing 40 parts (0.25 mole) of 25% sodium hydroxide solution. The solution was filtered to remove traces of insoluble particles, and to this, while agitating, there was slowly added 32 parts (0.375 mole) of 1,3-dimethylcyclopentanemethylamine. After stirring for a few minutes after the amine had all been added, 50 parts of 25 sulfuric acid solution were added very slowly with continuous agitation, whereupon 22.32 parts of sodium hypochlorite (0.3 mole) in the form of a water solution thereof, were slowly added while holding the temperature of the mass between 25-30" C. After all the *Batente'd May '95, "-1959 :2 hypochloritehad been introduced, agitationof "the mass was continued for aboutan hour and then a small portion (about12 parts) ,of sodiumsulfite was added,'while agitatingto destroy any unreacted oxidizing agent present. The entire mass was then cooled to below 25 C. and extracted with ether. After filtering to remove any disulfides present as ether insoluble material, the ether extract was repeatedly washed with water until the washings reacted neutral to litmus. The ether extract was ;then dried of moisture by means of anhydrous sodium sulfate andthe ether removed in vacuo at a maximumtemperature of 30 C. The product remaining was aviscous oil, amber in color, and was soluble in ether, acetone, benzene, chloroform, ethanol and ethyl acetate and was insoluble in 'heptane and water. It was obtained in 87.6% yield. The compound named at thecommencementof this -example possesses the empirical formula C H N S ,-which was identified as the product formed by analysis, as

evidenced by the results:

Percent Percent Theory Found Nitrogen 9. 58 9,.30

5-chlor0 -N (1,3 dimethylcyclopentylmethyl '2- benzothz'azalesulfenamide Percent Rercent Theory" Found Nitrogen M .895? 8. 74 Chlorine 10:85 11.15

EXAMPLE a -rnonucr c 6 ethoxy N (1,3 dimethylcyclopentylmethyl 2 benzothiazolesulfenamide As another example of the invention, a slurry was prepared of 52.18 parts -(-0.25-) mole of -6-ethox-y mercaptobenzothiazole in 25 parts of water containing 40 parts (0.25 mole) of 25 sodium hydroxide solution. While agitated there was slowly added thereto 63.6 parts (0.5 mole) of 1,3-dimethylcyclopentanemethylamine. After complete agitation, and with continuous stirring, there was then slowly added 50 parts of 25 sulfuric acid. Thereupon there was slowly added 22.4 parts (0.3 mole) of sodium hypochlorite in the form of a solution (138 ml. of a 16.1% solution). During the addition of the hypochlorite and for approximately a period of an hour thereafter, the temperature of the mix was maintained between 45-50 C. After this there was added to the stirred mixture about 4 parts of sodium sulfite to destroy any excess of hypochlorite present. After cooling to 25 C. or less, the reaction mixture was extracted with ether and the mixture filtered to remove traces of disulfide present. Thereupon the ether solution was repeatedly washed with water until the washings were neutral to litmus, the solution was then dried of water droplets by means of anhydrous sodium sulfate and the ether was then removed'in vacuo. A viscous oil, amber in color, wasobtained in 81.2% yield as the desired reaction product. This product exhibited the same solubility characteristics as did the products of Examples 1 and 2. Identityofthe product (empirical formula C H N OS was proved by analysis as shown by-the results:

Percent Percent Theory Found Nitrogen 8. 33 8.00

As an example of the accelerating activity of the products now claimed, tests were carried out on stocks prepared in the usual manner from the following recipes, all in parts by weight;

Stock A, Stock B, Parts by Parts by Weight weight Smoked sheets rubber 100 100 Carbon black (Phllbleck O) 50 50 Zinc oxide 5 Stearic acid 3 3 Saturated hydrocarbon softener 3 3 Sulfur 2. 5 2. 5 Antioxidant 1.5 1.5 Product A 0. 5 Product B 0. 5

The stocks so compounded were cured in the usual manner by heating in a press for various periods of time at a temperature of 144 C. The modulus and tensile properties of the resulting products are set forth below:

TABLE I Modulus of Cure Elasticity in Tensile at Stock Time in lbs./in. at; Break in Elongation at lbs/in.

The scorch delay of the uncured compositions was evaluated by means of a Mooney plastomcter. The time required for incipient vulcanization or scorch was taken at the point on the plasticity curve when the plasticity began to rise continuously:

TABLE II Mooney Scorch Stock in Mins. at

4 l t It is intended to cover all changes and modifications of the examples of the invention herein chosen for purposes of disclosure which do not constitute departures from the spirit and scope of the invention.

What is claimed is: 1. As a new product a sulfenamide of the structure R-B-fi-R; where R is a radical selected from the group consisting of benzothiazolyl and lower alkoxy, lower alkyl, phenyl and chloro substitution products thereof and R is a hydrocarbon radical having the carbon linked to nitrogen further linked to lower alkyl substituted cyclopentyl, residual valances on the aforesaid carbon being satisfied by a member of the group consisting of hydrogen and lower alkyl radicals.

2. As a new product a sulfenamide of the structure H R-S-N-CHr-R where R represents a benzothiazolyl radical and R represents an alkyl cyclopentyl radical containing at least one but not more than four lower alkyl substituents.

3. As a new product a sulfenamide of the structure H RSNR1 wherein R represents a benzothiazolyl radical and R rep resents a di(lower alkyl) cyclopentylmethyl radical.

4. As a new product a sulfenamide of the structure H R-S-N-Ih wherein R represents a benzothiazolyl radical and R represents a dimethylcyclopentylmethyl radical.

5. As a new product a sulfenamide of the structure R-s- N -R, wherein R represents a chlor substituted benzothiazoly radical and R represents a dimethylcyclopentylmethyl radical.

6. As a new product a sulfenamide of the structure References Cited in the file of this patent UNITED STATES PATENTS 2,129,621 Lichty Sept. 6, 1938 2,191,657 Harman Feb. 27, 1940 2,354,427 Carr July 25, 1944 2,382,793 Howland Aug. 14, 1945 

1. AS A NEW PRODUCT A SULFENAMIDE OF THE STRUCTURE 